A YouTuber received an ominous comment. Months later, 14 school students were massacred.

Nearly five months ago, 36-year-old Youtube vlogger Ben Bennight was alarmed by a comment left on one of his videos by a user named ‘Nikolas Cruz’.

“I’m going to be a professional school shooter,” it read.

Immediately, he alerted the FBI and flagged the comment with YouTube, who removed the comment.

The next day, they paid him a visit.

“They came to my office the next morning and asked me if I knew anything about the person,” Bennight told BuzzFeed News. “I didn’t. They took a copy of the screenshot and that was the last I heard from them.”

That was September. On Thursday, a 19-year-old by the name of Nikolas Cruz walked into the Marjory Stoneman Douglas High School in Parkland and opened fire on his ex-classmates, killing 17 and injuring more than 15 others.

A day after the mass shooting, the FBI confirmed they were warned of the ominous message, though after numerous checks, could not pinpoint his whereabouts.

“No other information was included with that comment which would indicate a time, location, or the true identity of the person who made the comment,” FBI Special Agent Rob Laskey said in a press conference on Thursday.

“The FBI conducted data reviews, checks, but was unable to further identify the person who actually made the comment.”

***

Nikolas Jacob Cruz and his brother Zachary were adopted shortly after the gunman was born, in August 1998, by Lynda Cruz and Roger Cruz.

When Cruz was just six years old, his father passed away after a heart attack. In November last year, at the age of 68, Lynda died of pneumonia, leaving both boys orphaned.

Barbara Kumbatovich, Cruz’s aunt, told The Miami Herald she believed her nephew was on medication dealing with emotional issues and that before she died, her sister was “struggling” with her son “the last couple years”.

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According to the The Sun-Sentinel, after Lynda died, the brothers moved in with a family friend, though Cruz wasn’t happy there. Instead, he reached out to a friend who he knew from his time at Stoneman Douglas – he had been expelled from there last year – and asked if he could move in with his friend’s family.

In a statement, Jim Lewis, an attorney working on behalf of that family, said the family who Cruz later moved in with were “devastated”.

“The family is devastated, they didn’t see this coming. They took him in and it’s a classic case of no good deed goes unpunished,” Lewis said. “He was a little quirky and he was depressed about his mum’s death, but who wouldn’t be?”

He “threatened to bring the guns to school multiple times,” senior Eddie Bonilla told the news outlet. Others said he “threw jokes around that he’d be the one to shoot up the school.”

One more, Sebastian Toala, told NBC he was never close with Cruz because he “always had a feeling there was something wrong”.

Joshua Charo, another former classmate, told the Miami Herald Cruz spoke often of “guns, knives and hunting.”

“He used to tell me he would shoot rats with his BB gun and he wanted this kind of gun, and how he liked to always shoot for practice,” he said.

On Thursday, the leader of a white nationalist militia said Cruz is a member of his group, adding he has participated in paramilitary drills in Tallahassee.

Jordan Jereb told the Associated Press he did not know Cruz personally, that he believed the suspect acted alone and suggested the fact the shooting occurred on Valentine's Day was intentional because of Cruz’s “trouble with a girl".

“He acted on his own behalf of what he just did and he’s solely responsible for what he just did," he said.

Broward County Sheriff Scott Israel also revealed social media accounts believed to belong to Cruz - the photos in which have since been deleted - had posts he considers “very, very disturbing”.

According to the Evening Standard, in several Instagram accounts, a man believed to be Cruz is seen posing with a selection of knives and guns.

On Friday, after the 19-year-old admitted to the shootings, Judge Kim Theresa Mollica upheld the prosecutors’ request that Cruz be held in custody without bond until further notice.

Fixated on violence, and with - it would seem - a grand plan to die a mass murderer, Nikolas Cruz wasn't evasive in telling the world about his intentions.

We just missed all the signs.